Impulse sender



July 9, 1940. x 2,207,506

IMPULSE SENDER Filed Dec. 16, 1937 INVENTOR.

IRVI ATTORNEY.

Patented duty 9, i940 Application December 116, lllti, Serial No.l3l,l2l

4 (Claims.

The present invention relates in general to impulse senders, and moreparticularly to calling devices for automatic telephone systemsorsignalling systems.

An object of the invention is the production of a device of thischaracter that will handle heavy currents without arcing.

Another object is to provide improved contact operating means forimpulse senders.

A further object of the invention is toproduce an improved device ofthis character that may be used in locations that are hazardous becauseof the presence of explosive gases that may be ignited by an electricarc.

Another object is to operate the contacts of an electrical make andbreak device by d rect magnetic action Without intermediate icallinkage.

A feature of the invention is contact spring arrangement completelysealed in an evacuated glass tube, the springs being operated by theturning of a permanent magnet.

A further feature is the elimination of wear, due to friction, on thecontact spring and the cam co-operating with it, by operating thecontact without physical connection with the contact operating means.

When direct current impulses are transmitted over a line containinginductance, an inductive discharge inevitably results from the openingof the circuit, and is manifested at the opened contacts by the presenceof a spark. In hazardous locations that may be exposed to the presenceof explosive gases, such as in a dirigible, in a mine, or in similarlocations, the producton of a spark is highly undesirable. In theinstant invention the production of a sparkdue to inductive discharge isinhibited by the fact that the impulsing contacts are in a vacuum.Furthermore, any spark that may develop will have no efiect since thepoint of sparking is effectively insulated from the atmosphere by thesurrounding vacuum. Another advantage of such construction is in thepractical elimination of inductive interference to neighboring radioreceivers.

The improved contact arrangement and operating means has been applied toa calling device of the type shown in Obergfell Patent No. 1,642,822,patented September 1927 The invention is illustrated in the accompanyingdrawing comprising Figs. 1 to 5, in which:

Fig. 1 is a rear view of the calling device of the above-mentionedpatent modified to include the features of the instant invention;

Fig. 2 is a side view of the complete device;

(iCi. me es) 3 is an enlarged side view oi the evacuated glass tubecontaining a pair of impulse springs;

4 is an end section of Fig. 3, taken along the line i d;

Fig. 5 is a side view of the mounting detail or the tube.

The calling device of the instant invention is substantially identicalwith that shown in the hereinbefore mentioned patent, modified to theextent that the impulse cam has been replaced by a iJ-shaped permanentmagnet and the exposed impulse springs have been replaced by a pair ofimpulse springs enclosed within a hererratically sealed glass tube.

Referring now to Figs. 3 and 4, it will be seen that the impulse sendingsprings 23 and 2d are enclosed within an evacuated glass cylinder 29,the exposed portions of the springs serving as terminals for theconnection of Wires. Spring 23 atits inner end has welded to it a shortlength of Wire 22 to form a contact. Spring 26 at its inner end bears ani..-shaped length of wire 2i forming a contact to cooperate with contact22. In addition spring 2d has welded to its underside, a length ofmagnetic material 25 which is approximately the length of the magnet iiiIncas-- ured from the outer sides of the pole faces. The vacuum contactunit is so made that the contacts 2i and 22 are normally held apart bythe tension of springs 23 and 2d.

Referring now to Fig. 2v the vacuum contact unit is clamped to bracketit, which is in turn adjustably mounted on an L-shaped bracket it, bymeans of screws it. This adjustment is provided to vary the distancebetween the springs and the permanent magnet in order to provide forvarious impulse ratios. In its normal position, the permanent magnet i2is mounted on the driving spindle of the calling device by means of nutsii and It, in a direction parallel to the longitudinal axis of themagnetic element 25. In this position, spring Ed is attracted to themagnet l2 and the contacts are closed, corresponding to the usualconstruction of such calling devices. When the finger hole plate I9 isturned from its normal position and allowed to restore, to send a singleimpulse, the magnet l2 starts to turn about its axis, thus widening theair gap between the pole faces and the magnet element 25. Beforereaching a point at right angles to its normal position the magnet fluxflowing in the circuit is decreased, due to the increased air gap andconsequent increase in reluctance, to such a degree that spring 24 ispermitted by its own spring tension to restore to a iii normal position,with contacts 25 and 22 separated.

The magnetic attraction, of course, is at a minimum when the magnet isat right angles to the length of the spring and varies gradually indegree in proportion to the angular displace-. ment of the magnet. Asthe magnet passes its point of minimum attraction and continues to itsnormal point of rest the magnetic attraction increases gradually untilit is suficient to overcome the tension of spring 21% and again closecontacts 2! and 22 to terminate the impulse.

It will be seen, therefore, that for each onehalf revolution of themagnet, one impulse is produced, and in this respect is identical inoperation with the calling device of the patent previously referred to.

As mentioned previously, thevacuum tube is adjustably mounted on bracketa, this adjustment being made possible by the slotted holes 58 inbracket It. In this way it is possible to vary the distance between themagnet and the elements of the tube to provide the most desirable timeratio between make and break of the contacts.

Although the invention has been described with reference to a specificstructure, a number of modifications will at once suggest themselves.For instance, the magnet may be turned at right angles to the positionshown, in which case the contacts will remain normally open, beingclosed intermittently instead of being normally closed, then openedintermittently. Again, the contacts 25 and 22 may be disposed adjacentthe lower side of spring 23 instead of the upper side as shown. Thisconstruction also will produce closed circuit pulses but without thenecessity of turning the magnet at right angles.

The vacuum tube has been described as being evacuated. Alternatively,the tube may, instead of being evacuated, be filled with an inert fluid.

What is claimed is:

1. In an impulse sending device, a manually operable dial, a magnet,means including a gear train for rotating the magnet a number ofrevolutions dependent upon the angular lacement of the dial. impulsesprings, means for so mountaao'aaoe ing said springs with respect to thepath of said magnet that said springs are operated by magnetic influenceduring a portion of each revolution of the magnet, said last meanspermitting the mounting of said springs with respect to the path of themagnet to be varied to proportion the amount of each revolution of saidmagnet during which said springs are influenced.

2. In an impulse sending device, a pair of contacts within ahermetically sealed vessel, a magnetic element forming a part of one ofsaid contacts, a U shaped magnet having pole faces and pivoted at apoint midway between said pole faces, said pole faces adapted to bepositioned along the longitudinal axis of said element or perpendicularto the longitudinal axis thereof in dependence upon the position of themagnet, both of said pole faces lying at all times in a plane paralleland adjacent to one side of said element, a manually operable member,and means responsive to a single manual operation of said member formoving said magnet and said pole faces alternately from one oi saidpositions to the other for operating said contacts, the number of saidalternations dependent upon said single manual oper- 2 ation of saidmember.

3. In a device as claimed in claim 2, wherein said contacts and saidvessel comprise a unitary structure, means for varying the distancebetween said structure and said pole faces.

4. in a circuit controlling device, a rotating magnet, said magnethaving a plurality of pole faces all lying in the same plane andremaining in said plane continuously during the rotation of the magnet,circuit controlling springs, a magnetic member associated with saidsprings, said member normally at rest adjacent to said plane andoperated by the magnet during a portion of each revolution thereofthereby 'to actuate said springs, and means for varying thepositionoccupied by said member when at rest with respect to said planethereby to proportion the amount of each revolution during which saidmagnet shall operate said member. v

IRVIN W. COX.'

